MATLAB: Toolbar pushbutton not receiving updated strings from figure handles. - matlab

Question

I have a GUI with an edit box and a push button on the tool bar (well, more things than that, but those are the only things that matter!) Anyway, I have it so when you press the push button tool a variable is set to equal the string in the edit box. A simple var = get(handles.edit1, 'string'). However, when I go straight from entering the value in the box to clicking the pushbutton (without clicking anywhere else or pressing return), var is assigned the previous value in the edit box. Why is this? Is there any way to make sure the push button tool will pick out the correct value?
The GUI was made using guide, if that matters.

Answer 1

This is happening because the uipushtool callback is executing before the text box has time to 'validate'. There is surely a more elegant way to do that but this trick works:
You can use the waitfor command to tell the uipushtool callback to wait for the editable box to validate its input. Unfortunately is is not exactly enough so we'll have to:
1) pass the focus to a dummy control (I created a dummy pushbutton named pushbutton1 which does nothing. The focus could be send to any other dummy control.
2) now wait for the text box to validate its content.
3) When the text box is done, then retrieve the content the traditional way.
This method requires:
- A dummy control to send the focus to (but you can use a real one too)
- An dummy (or not) callback function for your editable box. (the waitfor instruction will wait for the callback to finish, if there is no callback, it will error
function uipushtool1_ClickedCallback(hObject, eventdata, handles)
uicontrol( handles.pushbutton1 ) ; %// pass the focus to a dummy control
waitfor(handles.edit1,'String'); %// wait for the editable box to validate its content
var = get(handles.edit1, 'string') ; %// now retrieve the editable box content
set( handles.text1 , 'String' , var ) %// this can be deleted, just to verify the method
% --------------------------------------------------------------------
function edit1_Callback(hObject, eventdata, handles)
%// This is the dummy callback function for the editable box
%// Do absolutely nothing here (or do if you want ... your choice)
EDIT
as I feared, my initial solution was too dirty to be robust enough. With 2 (or more) textboxes, I tried a large number of things but without success. I dropped the waitfor, I noticed that in some case, when the uipushtool was pressed, the callback of the editbox would fire but the uipushtool would not execute at all ... so i tried to managed things directly from the editbox callback => from the editbox keypressedFcn send each character as we type to a variable ... but even this editbox callback doesn't know the content of the edit box at the time it is executed ?? (This link provide a very simple example to reproduce that).
So to my great own disappointment, I had to resort to an 'external' solution. (If you accept that it becomes very simple though). The trick is to retrieve the handle of the Java EditBox object. Once we have the handle, getting the "real time" content is just matter of converting the Java string into a Matlab string.
To retrieve the Java object handles, you need the function FindJObj from Matlab central.
Put that anywhere in your matlab path, then the code for your pushbutton become something like :
To make sure there was no interferences between the text boxes and the uipushtools I made 2 separate uipushtools each controlling 1 editbox
function uipushtool1_ClickedCallback(hObject, eventdata, handles)
jEditbox = findjobj(handles.edit1); %// get the handle of the java editbox #1
var = char(jEditbox.getText) ; %// retrieve Java string and convert it to matlab string
disp(['uipushtool1_ClickedCallback running. Textbox1 content = ' var ]) %// debug line, you can delete or comment that
% --------------------------------------------------------------------
function uipushtool2_ClickedCallback(hObject, eventdata, handles)
jEditbox = findjobj(handles.edit2); %// get the handle of the java editbox #2
var = char(jEditbox.getText) ; %// retrieve Java string and convert it to matlab string
disp(['uipushtool2_ClickedCallback running. Textbox2 content = ' var ]) %// debug line, you can delete or comment that
Thanks to Yair Altman for the findjobj function, and many other contributions for Matlab users.

Answer 2

I tried to replicate your problem and created a new GUI using guide with only a pushbutton and an edit field. If I set the button callback to:
function pushbutton1_Callback(hObject, eventdata, handles)
get(handles.edit1,'string')
it always prints the current value of the edit field, no matter if I click somewhere else after entering the value or not. Which version of Matlab are you using? I've tested it using Matlab 2010a.